The efficiency of a naturally aspirated standard four-cycle gasoline (petrol) internal combustion engine is limited with respect to compression ratio and pre-ignition compression high pressure temperatures. This is because of the need to avoid pre-ignition temperatures close to the fuel's auto-ignition temperature threshold, beyond which the knocking effect will impair efficiency and reduce engine life. As a consequence of this pre-ignition temperature, standard four-cycle engines are typically limited to a low compression ratio (CR), a parameter that is defined as the ratio of the entire engine cylinder volume divided by the combustion chamber volume. For Standard Engines using standard gasoline fuel, CR is typically not greater than 11, which limits engines pre-ignition compression pressure of not more than 22 Bars.
Because of fuel auto-ignition temperatures, typically compression ratios chosen by engine manufacturers are between CR=9.5 and CR=11.8 for naturally aspirated engines. These values can vary but they are always less than CR=15.
These temperature and pressure constraints of the standard four-cycle engine design not only reduce engine efficiency, but they also result in larger and heavier engines and impose restrictions on the type of fuel that these engines can combust without knocking.
The present invention proposes a four-cycle internal combustion engine design with a permanent curtailed intake process, for which we will use short term “CIP” engine (“Curtailed Intake Process” engine), and consequently it has a curtailed compression process as well. As will be explained herein, this design allows the temperature and pressure of intake air to the combustion cylinders to be controlled, so that a much higher compression ratio CR and pre-ignition compression pressure can be achieved without approaching the auto-ignition threshold. Moreover, because this novel design can effectively regulate and set the maximum pre-ignition temperature of the fuel-air mixture, it can combust virtually any type of liquid hydrocarbon fuel without danger of knocking if the engine is designed for the lowest auto-ignition-temperature fuel to be used.
The four-cycle engine of the present invention, due to its much higher compression ratio, generates power equivalent to or greater than a standard four-cycle engine in a smaller and lighter engine and in an environment where all main engine parameters are under control for maximum output and efficiency.